1. Field of the Invention
This invention relates to a piston having a crown with valve pockets that are cut via a cutter having a frustoconical rather than a cylindrical contour. This way, the valve pocket for both the intake and exhaust valves can be cut with the same cutter, and a maximum amount of piston material is preserved.
2. The Prior Art
Valve pockets are usually cut into the crowns of pistons to allow the intake and exhaust valves to extend into the combustion chamber and allow clearance between the valve and the piston. The pockets are usually cut by a rotating cutting device having a cylindrical contour. The cutting device cuts into the piston crown, either straight on or at an angle, to create the pocket or recess. The problem with the use of the cylindrical cutter is that even with an angled cut, too much of the crown is removed narrowing the distance to the first ring groove, reducing the strength and durability of the piston. In addition, with a cylindrical cutter, two different cutters are required to machine the intake and exhaust pockets, due to the variation in the size and clearance required by each of the intake and exhaust valves are different. This is inconvenient and expensive.